Tensile Property of Submicrocrystalline Pure Fe Produced by HPT-Straining

Abstract

The microstructure and the mechanical properties of pure Fe after HPT-straining at a rotation-speed of 0.2 rpm under a compression pressure of 5 GPa were investigated. The elongated grains with 300 nm thick and 600 nm long were observed at r = 1.5 mm away from the disk center regions after HPT-straining for 5 turns ( εeq = 45). The obtained Vickers microhardness in the submicrocrystalline Fe after 5 turns was around Hv 3.6 GPa. The engineering tensile strength and total elongation of the HPT-processed Fe for 10 turns were 1.9 GPa and 30 %. These facts suggest that HPT-straining leads to significant refinement of microstructure and increase in strength with good ductility.

Evolution of Mechanical Properties and Microstructures with Equivalent Strain in Pure Fe Processed by High Pressure Torsion

“…9(a) is less than the values reported in earlier works of Fe. [15][16][17][18][19][20] This can be attributed to the difference in carbon contents in the materials employed in individual experiments. Although the C content was not described explicitly except the study of Todaka et al, 16) which is 0.03% C, it must have been much higher than 11 ppm in the Fe used in this study.…”

“…Although the C content was not described explicitly except the study of Todaka et al, 16) which is 0.03% C, it must have been much higher than 11 ppm in the Fe used in this study. Very recently, Todaka et al 20) reported extraordinarily high tensile strength in the same high purity Fe after processing by HPT. The enhancement results in almost twice when compared with the present tensile strength despite the fact that the hardness is in almost the same level as the preset study.…”

“…[15][16][17][18][19][20][21][22][23] Although the studies on HPT of Fe [15][16][17][18][19][20] are concerned with pure Fe (so called Armco iron), little information was given for the content of C except the studies of Todaka et al 16,20) It appears that the C inclusion is sensitive to the strength and microstructure. It also appears that the strength is dependent on the total imposed strain and on the strain path for the grain refinement when Fe samples are processed by SPD.…”

Dry Sliding Wear Properties of Sub-Microcrystalline Ultra-Low Carbon Steel Produced by High-Pressure Torsion Straining

“…7,8) The material was annealed at 1273 K for one hour in pure argon atmosphere, and then cut and polished into discs of 10 mm in diameter and 0.85 mm in thickness for HPT-straining. The HPT process was carried out using anvils with a depression of 0.25 mm in depth and of 10 mm in diameter.…”

“…The Vickers hardness of HPTprocessed metals increases significantly with increasing the equivalent strain at the initial stages of straining, but saturates to constant values at certain strains. 5,6) It has been reported by Todaka et al 7,8) that the HPT-processed ultra-low carbon steel exhibited extraordinary high strength and ductility.…”